Balanced crank shaft



J. A. QLDSON BALANCED CRANKSHAFT Filed May 1e, 1927 2 sheets-sheet 1 mSUN NM NV NW Sw Oct.. 18,1927.

J. A. OLDSON BALANCED GRANKSHAFT Filed May 16, 1927. 2 Sheets-Sheet 2Patented st. 18, 1927.

ENT

ronn A. OLESON, or WORCESTER, ifi-Ass'AcnUSETTsl ASSIGNOR TowYMAn-GORDON COMPANY, OE WORCESTER, MASSACHUSETTS, A VCORPORATION OEMASSACHUSETTS.

RALANCED CRANK SHAFT.

i Applicatonrled May 16,

ticularly designed forV use inhigh speed au- V tomobile engines. Morespecifically vmy invention relates to a crankshaft of theelghtthrow,nine-bearing typein whichthe; crankpins are disposed in two planesvpositionedat r90o to eachother. c j

YIt is the general Object of my invention to provide a construction insuch crankshafts l0 by which the shaft is counter-balanced, bothstatically and.dynamically, by providing ing tegral Aforgedcounterweights g associated with the two end cranlrpins which lie in one1 plane andl with the' two center cranlrpins y y which lie ina plane at99 thereto. .These Y counterweights are so designed as to mainf tainthe` static balance ofthe shaft and valso to offset the dynamic coupleproduced byv the successive applicationof power inthe different cranksin the operation of the enoine. 4.

b To accomplish this purpose, each counterweight-is offset laterallyA ina direction opposed to that of the next vadjacent cranlrpin in thealternate plane.

My invention further relates to arrange-` ments and combinations ofparts which will `be hereinafter describedvand moreparticularlypointedout in the4 appended claims.

A preferred form and a modificationof. theinvention are shown inthedrawingsin which Y AFig.. l is a front elevationof an eightthrow,nine-bearing crankshaft embodying my improvements; y l j Fig. 2 is anend elevation thereof, looking in the direction of the arrow 2 in Fig.ll; Y

Figs. 3, 4, 5 and 6 are sectional end ele-V vations, taken alongthelines3-M-3, l4--4, 5-.5 and 66 respectively in Figil;

Fig. 7 is a front elevation Aofan eightthrow, nine-bearing crankshaft,showing a i modied construction;

Fig. 8 'is any end elevation, looking in the direction of the arrow 8 inFig. 7; and

Figs. 9 to 14 inclusive are sectional end elevations, taken on the lines9 9, 10-l0, ll-ll, 12*12, 13-13 and 14-14 respectively in Fig. 7

Referring particularly to Figs. l to 6, I have shown a crankshaft havingeight crankpins numbered 20 to 27 inclusive and having nine shaftbearings numbered to 38 inclusive. The cr'anlrpins 2t), 2l, 26 and 1927.ASerial No. 191,617.

2v7-lie in a. single plane, 22, 23, 24 and 25 lie in disposed at 90o tothe lirst plane.

VVThe cranlrpins 2l and 26 are at 180o from and the crankpins the.crankpins 2O and 27, and the crankpinsy 23 and 24 are at 180O from thecranlrpins 22 and 25. ,The cranlrpins 22 and 25 are behind the axis'ofthe shaft, as viewed in Fig. l, while the cranlrpins 23 and 24 are infront of the axis of the shaft. Each cr'ankpin is connected toitsadjacent shaft bearings by cheeks at each end of each cranlrpin. i

VThe crankpins 2l, 22, 25 and 26 are connected to their shaft bearingsby short straight cheeks, as indicated at 39 in Fig. 4 or V40V in Fig.5. The remaining crank oins 20, 23, 24 and 27 are connected to theirsliaft bearings by cheeks, such as 4l in Fig. 3 or 42 in Fig. 6, whichare extended beyond the associated shaft bearings and which are enlargedlaterally on one side to counterweights 44 and 45` (Figs. 3 and 6). Thecenter of mass of the counterweightl 44 is offset at an angle ofapproximately 45G from the line joining the centers of the associatedcrankpin and shaft bearing and is offset in adirection opposite to theposition of the nearest crankpin in the alternate plane. That is, thecounterweights 44 in Fig. l project forward from the plane of thecrankpins 20 and 2l and the crank 22 projects rearward f'rom Said plane.Y

Similarly the counterweights 45 project upwardly from the plane to thecrankpins 22 and 23, as viewed in Fig. l, while the nearest crankpin inthe alternate plane, namely the cranlrpin 2l, projects downward. I thusprov-ide*counterweightsvon the cheeks of the two end crankpins in oneplane and on the cheeks of the two center crankpins in the alternateplane,4 and by offsetting the counterweights as above described, Iproduce a shaft which is in static balance, as the counterweights are at180O from each other, and I also produce a shaft which is well balanceddynamically at all reasonable speeds, such as are encountered in actualoperation.

The counter-weights disposed as above described substantially eliminatethe tendency of the shaft to whip or bow outward between the endbearings 30 and 38, there being a marked tendency in such shafts whennot counterweighted to assume an outward provide an alternate plane ingsnumbered 60 to 68 inclusive. Each.

erankpin is connected to its adjacent crank bearing by two cheeks whichwith four exceptions are of the short and simple 'for-In indicated at 70(Fig.- l0), 71i (Fig. Il) 72 (Fig. I2) or 75 (Fig. 13). `lhe remainingcheeks are ofy the t-ype shown at 74 (Figi 9f)ior-75 (Fig.

It will b e noted? that the crankpins 50- and 5l are positioned 180apart in a single plane and that the crank-pins 52 and 53 are similarlypositioned i800 apart in an lalternate plane perpendicular to' the planeof the pins 50 and 51. As viewed in Fig. 7, ,the crankpins 52 and 55 areback ofthe axis of the crankshaft andthe crankpins 53 and 54 are forwardof the axis.

The end cheeks 74: are extended beyond the axis of the shaft bearing andare enflarged laterally as indicated "at 76 in Fig. 9, the center of thecounterwveight being on aline substantially at .455 from the linejoining the center of the associated crankpin and crank bearing. Thecounter-weightsare offset' in a direction opposite to the position ofthe nearest cranlkpin in the alternate planefas in the prefer-red forni.That is, the counter-weights 76 project forwardly while the ci'ankpiiis52 `and 55-project rear-A wardly as viewed in Fig. 7.

Similarly the center' cheeks 75 are provided. with counter-weights 77similarly olfset at an angle of approximately 450 and in a similardirection. That is, the counter'- weights 77 are projected upwardly, asviewed in Fig. 7, while the nearest crank,- pins 52Yand 55 in thealternate plane project downwardly. 'i

operation and advantages of this -construction are similar' to that ofthe preferred form, when suliicient Width can be obtained for theheavier counterweights 7(5- and 77. In many erankshafts, however, theaxial distance between bearings is reduced to a minimum, so that it isdifficult to get a sucipnt weight of metal in ra single counterweightbetween ay erankpin and one of its shaft bearings, and in such cases itis desirable t0 use the @Oesteiveehts in pairs instead 0f singly, asshew@ ,iii FiaV 1- -A crankshaft constructed' as above described, withthe double counterweights shown in Figs. l to 6 or with the singleeounterweights shown in Figs. 7 to 14, has been found very satisfactoryin luse, greatly reducing the vibration ofthe shaft when in rapidrotation, and correspondingly increasing the smoothness of the ruimingof the engine. i

Having thus described iny invention and the advantages thereof I do notwish `tobe limited to the details herein disclosedY otlier wise than asset forth in the claims, but what I claim iszi. An eight-thrownine-bearing crankf shaft having crank-pins disposed in two planespositioned perpendicular to each other, said crankpins being positionedon` opposite sides of the axis in each plane, and said crankshaft havingcounterwe-ights forged integral with said shaft and associatedvwilthfthe two end crankpins and with the two middle crankpins only,thecentei' of niass of each counterweight 'being offset at anV angle ofsubstantially 450 fromv its asso, ciated crank cheek and away from thenear#4 positioned perpendicular to eachother, said crankpins beingpositioned on opposite sides of the axisinfeach plane, and said?crankshaft having counterweights forged 4integral l with said shaft andassociated in pairs with the two en d crankpins and with the two middlecrankpins only, the center of mass of. each counterweight being offsetat an angle of substantially 45o from its associatedcrank cheek andvaway from the nearest crankpin in the plane perpendicular to said cheek,the end andl 'center counterweights being spaced diametricall apart.

In testimony ereof I have lhereunto aixedmysignatnre. Y 'JOHN A.OILDSON.

